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<span id="MPI-Files-and-Data-Types"></span><div class="header">
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<span id="MPI-Files-and-Data-Types-1"></span><h4 class="subsection">6.12.1 MPI Files and Data Types</h4>

<p>All programs using FFTW&rsquo;s MPI support should include its header file:
</p>
<div class="example">
<pre class="example">#include &lt;fftw3-mpi.h&gt;
</pre></div>

<p>Note that this header file includes the serial-FFTW <code>fftw3.h</code>
header file, and also the <code>mpi.h</code> header file for MPI, so you
need not include those files separately.
</p>
<p>You must also link to <em>both</em> the FFTW MPI library and to the
serial FFTW library.  On Unix, this means adding <code>-lfftw3_mpi
-lfftw3 -lm</code> at the end of the link command.
</p>
<span id="index-precision-6"></span>
<p>Different precisions are handled as in the serial interface:
See <a href="Precision.html">Precision</a>.  That is, &lsquo;<samp>fftw_</samp>&rsquo; functions become
<code>fftwf_</code> (in single precision) etcetera, and the libraries become
<code>-lfftw3f_mpi -lfftw3f -lm</code> etcetera on Unix.  Long-double
precision is supported in MPI, but quad precision (&lsquo;<samp>fftwq_</samp>&rsquo;) is
not due to the lack of MPI support for this type.
</p>



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